depends on what your putting in.. I have 3 heads in my 150 with a total of 5300 gph...And I have bouight a dual head powerhead off ebay.. Been running about 6 mos now no peoblems.. couldnt beat the 19 dollar price tag thought it would be junk, but for the price got it anyway.. still going strong.. so I left that in and kept the other koralia for a spare